Abstract: Resolving the tension between quantum superpositions and the uniqueness ofthe classical world is a major open problem. One possibility, which isextensively explored both theoretically and experimentally, is that quantumlinearity breaks above a given scale. Theoretically, this possibility ispredicted by collapse models. They provide quantitative information on whereviolations of the superposition principle become manifest. Here we show thatthe lower bound on the collapse parameter lambda, coming from the analysis ofthe human visual process, is ~ 7 +- 2 orders of magnitude stronger than theoriginal bound, in agreement with more recent analysis. This implies that thecollapse becomes effective with systems containing ~ 10^4 - 10^5 nucleons, andthus falls within the range of testability with present-day technology. We alsocompare the spectrum of the collapsing field with those of known cosmologicalfields, showing that a typical cosmological random field can yield an efficientwave function collapse.